[PATCH 0/2] Balance mutex_init and mutex_destroy calls

[PATCH 0/2] Balance mutex_init and mutex_destroy calls

[Maíra Canal]

This series introduces some changes to assure the correct resource release on
the V3D driver, especially the mutex. Currently, the V3D has no mutex_destroy()
calls, which means that a mutex is being instantiated, but it is not being
released by the end of its use.

So, use the DRM-managed mutex_init variants when possible to manage the mutex
release and add mutex_destroy() calls when not possible.

Best Regards,
- Maíra Canal

Maíra Canal (2):
  drm/v3d: switch to drmm_mutex_init
  drm/v3d: add missing mutex_destroy

 drivers/gpu/drm/v3d/v3d_gem.c     | 17 +++++++++++++----
 drivers/gpu/drm/v3d/v3d_perfmon.c |  2 ++
 2 files changed, 15 insertions(+), 4 deletions(-)

-- 
2.38.1

[PATCH 1/2] drm/v3d: switch to drmm_mutex_init

[Maíra Canal]

mutex_init() is supposed to be balanced by a call to mutex_destroy(), but
this is not currently happening on the v3d driver.

Considering the introduction of a DRM-managed mutex_init variant, switch
to drmm_mutex_init.

Signed-off-by: Maíra Canal <mcanal@igalia.com>
---
 drivers/gpu/drm/v3d/v3d_gem.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
index b8980440d137..96af1cb5202a 100644
--- a/drivers/gpu/drm/v3d/v3d_gem.c
+++ b/drivers/gpu/drm/v3d/v3d_gem.c
@@ -10,6 +10,7 @@
 #include <linux/sched/signal.h>
 #include <linux/uaccess.h>
 
+#include <drm/drm_managed.h>
 #include <drm/drm_syncobj.h>
 #include <uapi/drm/v3d_drm.h>
 
@@ -1075,10 +1076,18 @@ v3d_gem_init(struct drm_device *dev)
 
 	spin_lock_init(&v3d->mm_lock);
 	spin_lock_init(&v3d->job_lock);
-	mutex_init(&v3d->bo_lock);
-	mutex_init(&v3d->reset_lock);
-	mutex_init(&v3d->sched_lock);
-	mutex_init(&v3d->cache_clean_lock);
+	ret = drmm_mutex_init(dev, &v3d->bo_lock);
+	if (ret)
+		return ret;
+	ret = drmm_mutex_init(dev, &v3d->reset_lock);
+	if (ret)
+		return ret;
+	ret = drmm_mutex_init(dev, &v3d->sched_lock);
+	if (ret)
+		return ret;
+	ret = drmm_mutex_init(dev, &v3d->cache_clean_lock);
+	if (ret)
+		return ret;
 
 	/* Note: We don't allocate address 0.  Various bits of HW
 	 * treat 0 as special, such as the occlusion query counters
-- 
2.38.1

Re: [PATCH 1/2] drm/v3d: switch to drmm_mutex_init

[Daniel Vetter]

On Mon, Nov 07, 2022 at 07:46:55PM -0300, Maíra Canal wrote:
> mutex_init() is supposed to be balanced by a call to mutex_destroy(), but
> this is not currently happening on the v3d driver.
> 
> Considering the introduction of a DRM-managed mutex_init variant, switch
> to drmm_mutex_init.
> 
> Signed-off-by: Maíra Canal <mcanal@igalia.com>

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  drivers/gpu/drm/v3d/v3d_gem.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
> index b8980440d137..96af1cb5202a 100644
> --- a/drivers/gpu/drm/v3d/v3d_gem.c
> +++ b/drivers/gpu/drm/v3d/v3d_gem.c
> @@ -10,6 +10,7 @@
>  #include <linux/sched/signal.h>
>  #include <linux/uaccess.h>
>  
> +#include <drm/drm_managed.h>
>  #include <drm/drm_syncobj.h>
>  #include <uapi/drm/v3d_drm.h>
>  
> @@ -1075,10 +1076,18 @@ v3d_gem_init(struct drm_device *dev)
>  
>  	spin_lock_init(&v3d->mm_lock);
>  	spin_lock_init(&v3d->job_lock);
> -	mutex_init(&v3d->bo_lock);
> -	mutex_init(&v3d->reset_lock);
> -	mutex_init(&v3d->sched_lock);
> -	mutex_init(&v3d->cache_clean_lock);
> +	ret = drmm_mutex_init(dev, &v3d->bo_lock);
> +	if (ret)
> +		return ret;
> +	ret = drmm_mutex_init(dev, &v3d->reset_lock);
> +	if (ret)
> +		return ret;
> +	ret = drmm_mutex_init(dev, &v3d->sched_lock);
> +	if (ret)
> +		return ret;
> +	ret = drmm_mutex_init(dev, &v3d->cache_clean_lock);
> +	if (ret)
> +		return ret;
>  
>  	/* Note: We don't allocate address 0.  Various bits of HW
>  	 * treat 0 as special, such as the occlusion query counters
> -- 
> 2.38.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

[PATCH 2/2] drm/v3d: add missing mutex_destroy

[Maíra Canal]

v3d_perfmon_open_file() instantiates a mutex for a particular file
instance, but it never destroys it by calling mutex_destroy() in
v3d_perfmon_close_file().

Similarly, v3d_perfmon_create_ioctl() instantiates a mutex for a
particular perfmon, but it never destroys it by calling mutex_destroy()
in v3d_perfmon_destroy_ioctl().

So, add the missing mutex_destroy on both cases.

Signed-off-by: Maíra Canal <mcanal@igalia.com>
---
 drivers/gpu/drm/v3d/v3d_perfmon.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/v3d/v3d_perfmon.c b/drivers/gpu/drm/v3d/v3d_perfmon.c
index 48aaaa972c49..292c73544255 100644
--- a/drivers/gpu/drm/v3d/v3d_perfmon.c
+++ b/drivers/gpu/drm/v3d/v3d_perfmon.c
@@ -113,6 +113,7 @@ void v3d_perfmon_close_file(struct v3d_file_priv *v3d_priv)
 	idr_for_each(&v3d_priv->perfmon.idr, v3d_perfmon_idr_del, NULL);
 	idr_destroy(&v3d_priv->perfmon.idr);
 	mutex_unlock(&v3d_priv->perfmon.lock);
+	mutex_destroy(&v3d_priv->perfmon.lock);
 }
 
 int v3d_perfmon_create_ioctl(struct drm_device *dev, void *data,
@@ -177,6 +178,7 @@ int v3d_perfmon_destroy_ioctl(struct drm_device *dev, void *data,
 	if (!perfmon)
 		return -EINVAL;
 
+	mutex_destroy(&perfmon->lock);
 	v3d_perfmon_put(perfmon);
 
 	return 0;
-- 
2.38.1

Re: [PATCH 2/2] drm/v3d: add missing mutex_destroy

[Daniel Vetter]

On Mon, Nov 07, 2022 at 07:46:56PM -0300, Maíra Canal wrote:
> v3d_perfmon_open_file() instantiates a mutex for a particular file
> instance, but it never destroys it by calling mutex_destroy() in
> v3d_perfmon_close_file().
> 
> Similarly, v3d_perfmon_create_ioctl() instantiates a mutex for a
> particular perfmon, but it never destroys it by calling mutex_destroy()
> in v3d_perfmon_destroy_ioctl().
> 
> So, add the missing mutex_destroy on both cases.
> 
> Signed-off-by: Maíra Canal <mcanal@igalia.com>
> ---
>  drivers/gpu/drm/v3d/v3d_perfmon.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/v3d/v3d_perfmon.c b/drivers/gpu/drm/v3d/v3d_perfmon.c
> index 48aaaa972c49..292c73544255 100644
> --- a/drivers/gpu/drm/v3d/v3d_perfmon.c
> +++ b/drivers/gpu/drm/v3d/v3d_perfmon.c
> @@ -113,6 +113,7 @@ void v3d_perfmon_close_file(struct v3d_file_priv *v3d_priv)
>  	idr_for_each(&v3d_priv->perfmon.idr, v3d_perfmon_idr_del, NULL);
>  	idr_destroy(&v3d_priv->perfmon.idr);
>  	mutex_unlock(&v3d_priv->perfmon.lock);
> +	mutex_destroy(&v3d_priv->perfmon.lock);
>  }
>  
>  int v3d_perfmon_create_ioctl(struct drm_device *dev, void *data,
> @@ -177,6 +178,7 @@ int v3d_perfmon_destroy_ioctl(struct drm_device *dev, void *data,
>  	if (!perfmon)
>  		return -EINVAL;
>  
> +	mutex_destroy(&perfmon->lock);

This one looks wrong, I think this should be put into v3d_perfmon_put.
There is also an error case in v3d_perfmon_create_ioctl() that I think you
missed, right above the kfree(perfmon).

With these two fixes this is Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>


>  	v3d_perfmon_put(perfmon);
>  
>  	return 0;
> -- 
> 2.38.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch